This invention is an implantable medical device assembly for use in surgical procedures. It is most preferably an implantable structure having stenting properties but only partially coated with or partially associated with a material causing an angiogenic response. One variation of the invention is an artificial occlusion kit having the inventive implantable stenting structure situatable and vaso-occlusive devices. The inventive implantable stenting structure is typically situated so to prevent migration of artificial occlusion devices or implants from an occlusion site, such as an aneurysm, and into an adjacent body space, such as a blood vessel.
Different implantable medical devices have been developed for treating various ailments associated with body lumens, such as ailments of body vessel walls or other lumenal walls. One category of implantable medical device that has been developed for artificial occlusion of body spaces is the category of xe2x80x9cartificial occlusion devices.xe2x80x9d Although artificial occlusion devices are useful in occluding body spaces, other applications include the occlusion of body lumens. Examples of lumens that have been identified as candidates for treatment with artificial occlusion devices include, for example, the vas deferens or the fallopian tubes. Most commonly, however, artificial occlusion devices have been disclosed for medical treatment of the vascular lumens and aneurysms in the walls of such vessels. This treatment is commonly referred to as xe2x80x9cartificial vaso-occlusion.xe2x80x9d
Artificial Vaso-Occlusion
Artificial vaso-occlusion is a medical treatment that has involved techniques such as the delivery of various occlusive agents including solidifying suspensions, thrombogenic fluids, solublized polymeric compositions, or emboli such as hog hair or suspensions of metal particles. Delivery of such agents or emboli normally causes a thrombogenic or other occlusive tissue response. Recent advancements in artificial occlusion of vessels and aneurysms have included the delivery and implantation of metal coils. Implantable metal coils that are useful as artificial occlusion devices in vascular lumens or aneurysms are herein referred to as xe2x80x9cvaso-occlusion coils.xe2x80x9d
Vaso-occlusion coils generally are constructed of a wire, usually made of a coils may be delivered through microcatheters such as the type disclosed in U.S. Pat. No. 4,739,768, to Engelson. The microcatheter commonly tracks a guide wire to a point just proximal of or within the desired site for occlusion. After removal of the guide wire, the coil is advanced through the microcatheter and out the distal end hole so to at least partially fill the selected space and create an occlusion.
Once a vaso-occlusion coil is implanted at a desired site, occlusion results either from the space-filling mechanism inherent in the coil itself, or from a cellular response to the coil such as a thrombus formation, or both. The space-filling mechanism of the vaso-occlusion coil may be either based upon a predetermined secondary geometry, or may be based upon random flow characteristics of the coil as it is expelled from a delivery sheath lumen.
Various commercially available vaso-occlusion coils have a secondary shape which dictates (at least in part) a space-filling occlusion mechanism. Such a secondary shape may include a secondary helical structure which involves the primary coil helix being itself wound into a second helix. In addition to the space-filling feature, another benefit to having a secondary coil shape is that it may allow the coil readily to anchor itself against the walls of a delivery site. For example, a vaso-occlusion coil having a secondary shape may be ejected from a sheath lumen where it was constrained in a stretched condition to have a first outer diameter equal to the sheath lumen inner diameter. When ejected, the coil passively expands to its secondary shape, often having a larger, second outer diameter to aid in space-filling the body cavity or lumen. This may be an expansion to the coil""s relaxed, unrestrained memory statexe2x80x94or at least until the coil encounters a vessel wall against which it exerts a force to complete the anchoring process.
One example of a type of vaso-occlusion coil having a pre-determined secondary shape is described in U.S. Pat. No. 4,994,069, to Ritchart et al. Ritchart et al describes a vaso-occlusive wire having a memory imparted thereto by heating the wire at about 800xc2x0 F. for 24 hours after it is shaped. This memory is effective to return the wire from a stretched, linear condition (in which shape it is advanced through a catheter) to a space-filling relaxed condition as the wire is released from the catheter. The diameter of the secondary shape may be approximately equal to or even larger than the vessel in which it is deployed.
In addition to vaso-occlusion coils having pre-determined secondary shapes that dictate in part their space-filling mechanism, other vaso-occlusion coils have been disclosed that take on random shapes when expelled from a delivery catheter. One such type of vaso-occlusive coil is often referred to as the xe2x80x9cliquid coil.xe2x80x9d An example of such a vaso-occlusive coil which takes on a random occlusive shape when delivered into a body space is shown in U.S. Pat. No. 5,718,711, issued Feb. 17, 1998, to Berenstein et al. This patent describes very soft, flexible coils which are flow-injectable through the delivery catheter using, e.g., a saline solution.
In addition to the various types of space-filling mechanisms and geometries of vaso-occlusion coils, other particularized features of coil designs, such as mechanisms for delivering vaso-occlusion coils through delivery catheters and implanting them in a desired occlusion site, have also been described. Examples of categories of vaso-occlusion coils based upon their delivery mechanisms include pushable coils, mechanically detachable coils, and electrolytically detachable coils.
One example of the type of vaso-occlusion coil referred to as the xe2x80x9cpushable coilxe2x80x9d is disclosed in U.S. Pat. No. 4,994,069 to Ritchart et al., introduced above. Pushable coils are commonly provided in a cartridge and are pushed or xe2x80x9cplungedxe2x80x9d from the cartridge into a delivery catheter lumen. A pusher rod advances the pushable coil through and out of the delivery catheter lumen and into the site for occlusion.
In contrast to pushable coils, mechanically detachable vaso-occlusion coils are integrated with a pusher rod and mechanically detached from the pusher after exiting a delivery catheter. Examples of such mechanically detachable vaso-occlusion coils are provided in U.S. Pat. No. 5,261,916 to Engelson, or U.S. Pat. No. 5,250,071 to Palermo.
Further in contrast to the mechanically detachable type of vaso-occlusion coil, the electrolytically detachable type is also integrated with a pusher rod, but is detached from the pusher by applying a direct current that dissolves a sacrificial link between the pusher and the coil. Examples of such electrolytically detachable vaso-occlusion coils are disclosed in U.S. Pat. No. 5,122,136 to Guglielmi et al, and U.S. Pat. No. 5,354,295 also to Guglielmi, et al.
Improvements for enhancing the thrombogenic or other occlusive tissue response to metal coils have also been disclosed. For example, vaso-occlusion coils having vaso-occlusive fibers attached thereto have been described (see for example, U.S. Pat. No. 5,226,911 to Chee et al.).
Vaso-Occlusion Coils in Aneurysms
A wide variety of clinical abnormalities in body lumens may be treated with artificial occlusion methods. For example, artificial occlusion methods have been disclosed for treating feeder vessels into tumors, arterio-venous malformations, fistulas, and aneurysms of vessel walls. Among arterial abnormalities, aneurysms present particular medical risk due to the dangers of potential rupture of the thinned wall inherent in an aneurysm. Occlusion of aneurysms with vaso-occlusion coils without occluding the adjacent artery is a desirable method of reducing such risk.
In one disclosed method of treating aneurysms with vaso-occlusion coils, a microcatheter is initially steered into or adjacent the entrance of an aneurysm, aided by a steerable wire. The wire is then withdrawn from the microcatheter lumen and replaced by the vaso-occlusion coil. The vaso-occlusion coil is advanced through and out of the microcatheter, desirably being completely delivered into the aneurysm. After or during delivery of such a coil into the aneurysm, a portion of the coil might then migrate out of the aneurysm entrance zone and into the feeding vessel. This may cause an undesirable response of occluding the feeding vessel. Also, there is an additional risk that the blood flow may induce movement of the coil farther out of the aneurysm, resulting in a more developed embolus in the good vessel.
One type of aneurysm, commonly referred to as a xe2x80x9cwide-neck aneurysm,xe2x80x9d is known to present particular difficulty in placing and retaining vaso-occlusion coils. Wide-neck aneurysms are herein referred to as aneurysms of vessel walls having a neck or xe2x80x9centrance zonexe2x80x9d from the adjacent vessel, which entrance zone has a diameter that either: (1) is at least 80% of the largest diameter of the aneurysm; or (2) is clinically observed to be too wide to effectively retain vaso-occlusion coils that are deployed using conventional techniques.
In attempting to prevent potential migration of vaso-occlusion coils from aneurysms, catheter distal tip shapes may be formed on delivery microcatheters to help support the distal tip during deployment of vaso-occlusive agents. However, this may provide only a partial solution, particularly in the case of wide-neck aneurysms. There is a need for a retaining device that a.) at least partially blocks an entrance zone to an aneurysm so that occlusion devices may be implanted in and retained within the aneurysm and are prevented from migrating through the entrance zone of the aneurysm and into the adjacent vessel, and b.) is at least partially coated with or associated with a composition causing an angiogenic response so to promote at least partial closing of the entrance to the aneurysm.
This invention is an implantable medical device assembly for use in surgical procedures. It is most preferably an implantable structure, perhaps having stenting properties, but that is only partially coated with a material having angiogenic properties or is partially associated with a material, e.g., a mesh or the like causing a localized angiogenic response. One variation of the invention is an artificial occlusion kit having the inventive implantable stenting structure and vaso-occlusive devices. The inventive implantable stenting structure is typically situated so to prevent migration of artificial occlusion devices or implants from an occlusion site, such as an aneurysm, and into an adjacent body space, such as a blood vessel. This invention includes a related method of use.
The inventive artificial occlusion kit is for the implantation and retention of an artificial occlusion device in a body space adjacent to and extending from a body lumen in a mammal. The artificial occlusion kit has at least one occlusion device suitable for filling at least a portion of the body space and a retaining device assembly at least partially coated with a material having angiogenic properties.
The retaining device of the artificial occlusion kit typically may be delivered and implanted at a retaining site in the body lumen adjacent to the body space to be occluded. Usually, this retaining device has a first shape that is radially expandable to a diameter that is sufficient to engage the wall of the body lumen at a retaining site adjacent the body space to be occluded. When engaged with the body lumen wall, the retaining device forms a lumen having a diameter that is sufficient to allow flow through that lumen, and also forms a barrier that prevents occlusion devices that are implanted in the body space from migrating out of the body space and into the adjacent body lumen. The inventive retaining device is either (or both) partially coated with a composition or associated with a composition or covering causing a localized angiogenic response. The angiogenic composition or covering is placed on the inventive retaining device at least in the region of the mouth of the aneurysm, generally in a quiescent region. This permits the angiogenic composition or covering to accelerate the formation of blood vessels in the mouth of the aneurysm and enhance the closure of the aneurysm.
In one retaining device variation, the expanded shape is a mesh or braid having the angiogenic composition or covering only exterior to the retaining device and only on, e.g., a portion of the circumference of the exterior of the device or a portion of the length of the device or with both of these configurations. The inventive retaining device may be self-expanding to a second shape with an expanded outer diameter upon delivery to the retaining site upon release at the retaining site. Alternatively, the retaining device may be balloon expandable from the first shape to the second or deployed shape.
In another variation of the invention, the retaining device may be a metal wire wound into a primary helix that has a secondary geometry which is also a secondary helix. This variation of the retaining device similarly includes the angiogenic composition or covering only exterior to the retaining device as deployed and only on, e.g., a portion of the circumference of the exterior of the device or a portion of the length of the device or with both of these coating configurations.
This invention includes methods for using the apparatus here described.